00自然-High-energy cathode material for long-life and safe lithium batteries英文资料.pdf

LETTERS
PUBLISHED ONLINE: 22 MARCH 2009 | DOI:
High-energy cathode material for long-life and
safe lithium batteries
Yang-Kook Sun1*†, Seung-Taek Myung2*, Byung-Chun Park1, Jai Prakash3, Ilias Belharouak4
and Khalil Amine4†
Layered lithium nickel-rich oxides, Li[Ni1−xMx]O2 (M = metal), Bulk
have attracted significant interest as the cathode material for Li( )O2 Interface
(high capacity)
rechargeable lithium batteries owing to their high capacity,
excellent rate capability and low cost1–7. However, their
low thermal-abuse tolerance and poor cycle life, especially
at elevated temperature, prohibit their use in practical
batteries4–6. Here, we report on a concentration-gradient Concentration-gradient
outer layer
cathode material for rechargeable lithium batteries based on a Li(¬x +y +z)O2
layered lithium nickel cobalt manganese oxide. In this material, 0 ≤ x ≤
each particle has a central bulk that is rich in Ni and a Mn-rich 0 ≤ y ≤
0 ≤ z ≤
outer layer with decreasing Ni concentration and increasing
Mn and Co concentrations as the surface is approached. The
former provides high capacity, whereas the latter improves the Surface
Li( )O2
thermal stability. A half cell using our concentration-gradient (high thermal stability)
cathode material achieved a high capacity of 209 mA